Method of making insulated multiconductor structures



Aug. 12, 1947. .J. T. MORGAN 2,425,294

METHOD OF MAKING INSULATED PAULJTICONDUCTOR STRUCTURES Filed. Dec. 18, 1944 4 2 Sheets-Sheet l Aug. 12, 1947. J. T. MORGAN 2,425,294

METHOD OF MAKING INSULATED MULTICONDUCTOR STRUCTURES Filed D86. 18, 1944 I 2 Sheets-Sheet 2 Jz I715. ji

H. J will H W v /i p// c a 7% a,

Jrvucmiom /&&m [Afar 222 Patented Aug. 12, 1947 METHOD OF MAKING INSULATED MULTI- CONDUCTOR STRUCTURES John T. Morgan, Charleston, W. Va.

Application December 18, 1944, Serial No, 568,770

Claims.

This invention is a. method by which a plurality of insulated conductors, or the multiple strands of a single conductor in coil formation may be embedded in a solid homogeneous body of dielectric material. Therefore, wherever the term "multi-wire insulated conductor is hereinafter employed in the specification and claims, it is intended to include as equivalent structure a cable of any desired length provided with a plurality of separate wires, registering portions of armature coils formed of a plurality of separate wires, or the registering multiple convolutions of a single wire in the form of a coil.

A common practice in the manufacture of multi-wire insulated coils is to first arrange a plurality of wires into a coil, with the ends of all of the wires projecting from the body of the coil to provide the usual leads. The wires used in initially forming the coil may be thinly insulated in suitable manner, such for instance by a coating of thin enamel, nylon or so-called formvar insulation, glass thread, or cotton covering.

The coil thus produced is then dipped in a varnish coating material, after which it is baked for an average period of 8 to hours. After completion of the baking stage the roughly formed coil is shaped by suitable means, such as a form or die so as to change the loop coil to the approximate form for fitting the armature. After the coil has been spread, the projecting ends of the wires are covered with sleeves of insulating material, leaving the extremities of the wires bare, so that they may be tinned" in a well known manner to insure perfection of electrical contact. The next step is to tape" the coil, 1. e., the body of the shaped coil is taped with a suitable tape, the taping being applied in such manner as to enclose the inner ends of the insulating sleeves.

on the leads. After taping, the body of the coil is dipped in a varnish coating material, the dipping thereof being followed by another baking stage lasting from 8 to 10 hours. The coil is then finally shaped in suitable manner to the precise contour necessary to meet the requirements of its use. A common method of shaping is to subject the coil to a hot-pressing step and then to a cold-pressing step.

One of the objects'of the invention is to provide a simple and inexpensive method of making multi-wire insulated conductors for use in the manufacture of armature and field coils, in such manner as to eliminate the taping, dipping and baking steps hereinabove described. A further object of the invention is to provide a method of making light, power and signal cables of multiwill normally be subjected while in use.

wire type which permits the bunching or assembling of the conductor into one cable, on the job," so as to suit conditions to be met by the contractor on the job location. An important object is to provide a simple and easily practiced method whereby allof -a plurality of insulated wires constituting the entire conductor, or any selected portion or portions thereof, may be embedded in a solid, homogeneous body of dielectric material of any desired cross-sectional contour.

The invention will be hereinafter fully set forth and particularly pointed out in the claims.

In the accompanying drawings- Figures 1 and 2 are diagrammatic top plan views illustrating the method of producing a cable-like multi-wire conductor.

Figure 3 is a transverse sectional view on the line it -3, Figure 1.

Figure 4 is a transverse sectional view on the line 44, Figure 2.

Figure 5 is a diagrammatic top plan view illustrating a modification.

Figure 6 is a diagrammatic plan view of another modification.

Figure 7 is a cross-sectional view on the line 'l--l, Figure 6.-

Figure 8 is a cross-sectional view on the line 88, Figure 6.

Figure 9 is a diagrammatic top plan view illustrating another modification of the method.

Figure 10 is a transverse sectional view illustrating a different modification.

Figures 11, 12 and 13 are diagrammatic views illustrating the method of producing anarmature coil.

Figure 14 is a view illustrating a modified method of making an armature coil.

Figure 15 is a diagrammatic view illustrating a field coil constructed of wire and made in accordance with the present invention.

Figure 16 is a similar view of a field coil constructed of a ribbon of metal.

Referring to Figures 1 to 4, both inclusive, a plurality of wires l0 covered with a thermoplastic insulation coating i i of any desired thickness are bundled in assembled parallel relation, as indicated at B. The wires may be coated with any desired thermoplastic material having the required dielectric properties, provided that it will not soften to such an extent that it would affect its insulation value and mechanical strength, at any temperature to which the finished conductor There are several known synthetic resins which can be readily modified to possess these qualities. For

3 example, polyethylene will meet the requirements of this process. Any desired number of wires may be assembled as indicated, the number depending upon the requirements for the particular installation, eight wires having been selected for purposes of illustration.

The assembled wires are welded together by subjecting them to heat of sufliciently high degree to soften their coatings H, and while said coatings are in the softened state they are molded together by suitably applied pressure. The molded body may be of any desired cross section, a rectangular form (Figure 4) having been selected for purposes of illustration and without intent to limit the invention in this respect. The dies employed may be of any well known structure capable of applying the desired heat and pressure.

If it is desired to supplement the thermoplastic coatings I0, 50 as to produce a more homogeneous cable, or to increase the volume of the insulation for the wires, when necessary to withstand higher voltages or to further protect the conductors from possibility of mechanical damage, the desired result may be accomplished in many ways. For purposes of illustration, reference is made to Figures 5, 6, 7, 8, 9 and 10. For instance, before placing the bundle B in the mold, it may be wrapped with a cord i2 of the same type of thermoplastic material as the coatings ll. See Figure 5. It will be readily understood that this cord i2 will be softened simultaneously with the softening of the coatings II, and the two will be pressed together into a homogeneous mass. Or a plastic cord I2 may be laid longitudinally of the bundle B as shown in Figures 6 and 7. By this arrangement the cord [2 acts as a filler to make a more homogeneous plastic-covered cable. It supplements the plastic insulation of the conductors II to make the outside plastic cover of the cable I more symmetrical. See Figure 8.

If desired, a thermoplastic tape I3 may be substituted for the cord II, as shown in Figure 9. Or, the bunch B may be placed within a split tube ll of any desired cross-section, made of thermoplastic material and then heat may be applied and the thermoplastic material pressed into a solid homogeneous mass. A cylindrical tube 14 is shown in Figure 10 for purposes of illustration.

If desired, the bundle of wires B may be arranged in a coil and then shaped for use as an armature coil, a field coil, or the like. In this connection, reference is now made to Figures 10, 11 and 12 which portray the stages of producing an armature coil made in accordance with the present invention. It is to be understood, how ever, in this instance the method of making an armature coil has been selected for purposes of illustration, and without intent to limit the invention in this respect because, except for the physical shape of the coil, the method followed is the same for all types of coil. In carrying out the method a bundle B3 of any number of wires i0, each coated with thermoplastic dielectric material is first roughly shaped to provide a coil C. Three wires have been selected for purposes of illustration. See Figure 11. It will be noted that the two extremities of each coated wire ID are projected from the body of the coil C in the same general direction, at opposite sides of said coil, so as to provide the necessary leads I5. The coil C is then Dressed in a well known manner to spread or shape it to the approximate contour of the finally completed coil C, as indicated in Figure 12, the parts l6 being shaped to enter the 4 slots of the armature. After spreading the coil the extremities of the lead wires are skinned" and tinned in a well known manner. The final stage is to subject the portions I6 of the coil C' to heat and pressure, such as by the well known hot-pressing method, for instance, to soften the coatings II at these locations, and then to mold the softened thermoplastic materialdnto a solid, homogeneous mass, similar to that described in connection with Figures ,2 and 4. The finished coil C" is illustrated in Figure 13, the portions of said coil C serving to stiffen the coil and having a shape to readily enter the armature slots. In Figure 14 is diagrammatically illustrated another method of making armature coils. Referring to said figure, a bundle of, wires Ill provided with the usual magnet wire tinsulation Ila: is shaped to the approximate con our 01' an armature coil C Opposite portions I of the coil C are then further insulated by the application thereto of thermoplastic insulation material of the same character as that already discussed in connection with the previously described forms of the invention. Said insulating material may be applied to the selected portions of the coil by any of the methods illustrated in Figures 5 to 10 both inclusive, but for purposes of illustration and without intent to limit the invention, said selected portions ISa are shown as being wrapped by a thermoplastic tape I3a, similar to that shown in Figure 10. The additional insulation is molded to the coil in suitable manner. For instance, for purposes of illustration, and without intent to limit the invention in this particular, each section 16a of the coil C and the associated supplemental insulation material are subjected to heat .and pressure within a suitable press P (Figure 14), so as to soften the thermoplastic material and then to mold into a homogeneous mass in each instance. The coil may then be shaped accurately to fit an armature slot by the hot press method described in connection with Figuresl 1, l2 and 13. Figure 15 diagrammtically illustrates ,a field coil FC constructed of the usual type of wire provided with thermoplastic insulation, similar to that already described herein, the insulation having been molded into a homogeneous mass by the method already fully described. Figure 16 is a. similar view illustrating a field coil FC constructed of a coiledribbon of metal, such as copper, with an interposed tape T of thermoplastic material which is interposed between the convolutions of the metal coil. The insulating material in this instance is also molded into a homogeneous mass between and around the metal tape, in the manner already described. The advantages of the invention will be read ily understood by those skilled in the art to which it belongs. For instance, an important advantage is the ability to manufacture, on the actual job installation, Of multi-wire conductors varying in number and sizes of the conductor elements, to meet the particular requirements of the installation. This is because the contractor is able to select and assemble conductors of proper carrying capacity with thermoplastic insulation possessing the required heat resistance and dielectric properties, and which are readily moldable into a solid jacket, thereby forming a homogeneous cable. Thus, the necessity of having cables manufactured in advance is avoided. Another advantage is the ability to readily and quickly produce multi-conductor cables of any desired number of conductors, encased in rigid dielectric material of any desired thickness, and of any required length. The inventure of field coils; armature coils or the like, in that it eliminates many of the steps now required to produce a durable coil, and ,yet provides a coil having higher dielectric and heat, moisture, acid and dirt resistance than coils of this type now in general use.

Having thus explained the nature of the invention and described an operative -manner of constructing and using the same, although without attempting to'set forth all of the forms in which it may be made, or all of the forms of its use, what is claimed is:

l. The method or making insulated multiconductor structures comprising bunching a plurality of electric conductors each provided with a coating of thermoplastic insulating material, enclosing the bunched wires with thermoplastic insulating material, softening the thermoplastic conductor coatings and the added thermoplastic insulating material, pressing the softened insua solid homogeneous mass, and cooling the solid mass.

2. The method 'of making insulated multiconductor structures comprising bunching a Plurality or electric conductors each provided with a coating of thermoplastic insulating material, applying a wrapping of thermoplastic insulating material around the bunched conductors,\ subjecting the wrapped portion to heat and pressure so as to first soften all of said thermoplastic material and then to mold the said softened material into a solid homogeneous mass. and cooling the solid mass.

3. The method of making insulated multiconductor structures comprising bunching a plurality of electric conductors each provided with a coating of thermoplastic insulating material, encasing the bunched conductors within a tube of thermoplastic insulation material. applying heat and pressure to the said tube and the enclosed bunch of conductors so as to first soften all of said thermoplastic material and then to mold the said softened material into a solid homogeneous mass, and cooling said mass.

4. The method of making insulated multiconductor structures comprising shaping a tion is cit-particular advantage in the manufac- 'lating material and the enclosed conductors into JOHN '17. MORGAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,306,625 Priest Jan. 10, 1919 7, 535,106 Heath, Mar. 5, 1895 1,449,371 Apple Mar. 27, 1923 1,213,726 Baclreland Jan.23 1917' 2,348,536 Gordo May 9, 1944 a 243,934, Mayal l.. .'July 5, 188 1 0 1,697,134 Neely Jan. 1, 1929 2,147,824 Webb Feb. 21, 1939 2,299,140 Hanson -1 Oct.20, 1942 2,234,523 Fischer et al. Mar. 11, 1941 i FoREici PATENTS Number Country Date 253,691 Great Britain June 24, 1926 368,743

bundle of conductor wires each provided with a coating of thermoplastic insulating material to the approximate, contour of an armature coil, attaching thermoplastic insulating material to selected portions of said coil, subjecting the selected portions of said coil and the associated insulating material to heat and pressure to first soften the thermoplastic material and said coatings then to press the same into a solid homogeneous mass, and then shaping the coil under heat and'pressure to accurately fit an armature slot.

5. The method of treating a preformed multiconductor structure the conductors whereof are each provided with a coating of thermoplastic insulating material and assembled in contiguous relationship; adding to the assembled conductors at a desired location a predetermined amount of thermoplastic insulating material, heat treating all the conductors and said added material at said desired location to soften all the thermoplastic insulating material, applying pressure to said softened material in said location to form a homogeneous mass, and cooling said mass.

Great Britain Mar/9, 1932 

